Pellet mill with bearing and wear translative element

ABSTRACT

This specification discloses an improvement in a pellet mill having a cylindrical feed receiver clamped to a radially perforated and cylindrical rotatable die. Rollers are disposed interior of the die for extruding feed through the perforated die into pellet form, the die being connected with a supporting cartridge by a ring clamp. The cartridge has an annular groove extending peripherally around a flanged portion, and an intermediate element is inserted in the groove to form a bearing and wear translative surface that engages the clamp.

United States Patent Inventor Charles R. Landers 5155 Winifred Drive. Fort Worth. Tex. 76133 App]. No 806,351

Filed Mar. 12, I969 Patented June I, 1971 PELLET MILL WITH BEARING AND WEAR TRANSLATIVE ELEMENT 10 Claims, 3 Drawing Figs.

US. Cl 107/14, 18/] 2 lnt.Cl A2lc 11/16 Field of Search 18/12 R; 107/14 P [56] References Cited UNITED STATES PATENTS 2,908,038 10/1959 Meakin 107/14X 2,994,918 8/1961 Landers l8/l2 FOREIGN PATENTS 870,597 6/1961 Great Britain 107/14 Primary Examiner-Billy J. Wilhite Att0rney-WotTord and Felsman ABSTRACT: This specification discloses an improvement in a pellet mill having a cylindrical feed receiver clamped to a radially perforated and cylindrical rotatable die. Rollers are disposed interior of the die for extruding feed through the perforated ie into pellet form, the die being connected with a supporting cartridge by a ring clamp. The cartridge has an annular groove extending peripherally around a flanged portion, and an intermediate element is inserted in the groove to form a bearing and wear translative surface that engages the clamp.

PATENTED JUN 1 Ian fl ATTORNEYS PELLET MILL WITH BEARING AND WEAR TRANSLATIVE ELEMENT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to mills for forming feed into pellets. More specifically, this invention relates to an improvement in a pellet mill having a perforated and cylindrical rotatable die with interior rollers for extruding the feed through perforations in the die to form pellets.

2. Background and General Discussion Previously, mills having a perforated and cylindrical rotary die have been used for forming feed into pellet form. Commonly, such machines have an interior roller for extruding feed through the die to form pellets and a hollow feed receiver for receiving the incoming feed and moving it into the interior of the die. The die and the feed receiver are serially connected with a cartridge by ring clamps. (See for example my US. Pat. No. 3,382,818.)

Although the prior art devices have been successful, they sometimes have a high incidence of repair caused by vibration of the elements of the machine against each other under the high forces generated by extruding the feed through the die. Excessive wear on the peripheral edge of the cartridge often results from the forceful vibrations. Repair is an expensive and time-consumingprocess requiring skilled craftsmen, such as welders and machinists, to build up and reform the worn edge of the cartridge. Frequently, such repairs necessitate returning the cartridge to the factory, with consequent freight expense.

To overcome the above-discussed problems, I have provided a significant improvement in such pellet mills. The flanged cartridge to which the die is removably secured has formed along its exterior or outer peripheral edge an annular groove. A bearing and wear translative element or ring, constructed of a material of generally different hardness than the cartridge, is secured in the groove and held in that disposition by the ring clamp. As a consequence, the unavoidable destructive and forceful vibrational movements between the ring clamp and cartridge do not cause the cartridge to deteriorate. Since the ring clamp and the intermediate element may be easily replaced, maintenance downtime and expense are significantly reduced.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary side elevation view illustrating a portion of a pellet mill employing the principles of my invention.

FIG. 2 is an end view of a bearing and wear translative element employed in the FIG. 1 embodiment of my invention.

FIG. 3 is a cross-sectional view taken along the lines from III-III of FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, the numeral 11 designates a cartridge assembly that includes a cartridge 13 upon which is secured a conventional perforated die 15 Die 15 is secured by means of a ring clamp 17, ordinarily consisting of three sections, each secured to each other by suitable fasteners 19, such as, the illustrated capscrews and nuts that extend through protuberant mating ears on the ends of each ring section. One or more keys 21 are provided to protrude from an exterior cylindrical surface of the cartridge 13 for engagement with slots in an outer portion (not shown) of the pellet mill to rotate the cartridge and die.

A main shaft 23 is adapted to extend through cartridge 13 to support a plurality of rollers 25 with indented surfaces that engage the interior cylindrical surface of the perforated die 15 for the purpose of extruding feed therethrough. The rollers are commonly supported on shafts secured in apertures in a frontal plate 26.. For additional disclosure of details of such pellet mills, refer to my U.S. Pat. No. 3,382,818.

A feed distribution arm 33 extends obliquely in preferably an auger fashion from a region adjacent perforated die 15, being secured in this position by a pedestal structure 35 and fasteners 34, 36 to the frontal plate 26 and to the main shaft 23.

A hollow feed receiver 41 is secured to the otherwise free end of the die 15 by another ring clamp 42 similar to the one previously described. Typically, exterior annular shoulders 45, 47 of the ring clamp extend into mating grooves formed on die 15 and feed receiver 41. A bushing 49 is generally provided between mating axial shoulders on the die and the feed receiver.

A central opening 51 is provided in a vertical wall 53 that forms the extremity of the feed receiver. Extending inward from the inner surface of the vertical wall are a plurality of radially spaced feed agitator elements 55. In this instance the agitator elements are manufactured of a thin metal plate having a vertical tab 57 secured by suitable means such as welding to vertical wall 53.

As the agitator elements 55 rotate into engagement with the feed, their oblique, planar surfaces 58 urge the feed downward at an oblique angle into engagement with the feed receiver, with the result that the feed is forced into the interior of die 15.

Rollers 25 force the feed through apertures in die 15 to form the desired pellet form. Because of the rotation and the force of the extrusion, the ring clamps tend to move slightly but rapidly with respect to their bearing surfaces. The most pronounced force and movement is suffered by the back side of the outer peripheral edge of the cartridge 13 where clamp 17 secures both die 15 and, ultimately, receiver 41 to the cartridge. To alleviate problems of repair, the bearing and wear translative element 59 is secured between ring clamp 17 and the outer peripheral back side or edge of cartridge 13. An annular groove 61 is formed peripherally around the back side or peripheral edge of the flanged portion of cartridge 13 and the translative element 59 is fitted into the groove. The groove 61 in cross section is preferably but not necessarily, in the form of a triangle, ideally an isosceles right triangle, as is the translative element as seen in longitudinal cross section. The ring clamp 17 has inwardly protruding shoulders 60, 62, one of which 62 is received by a mating groove in the die 15. The other shoulder 60 extends over the mating bearing surface 67 of the translative element 61, the inner surface of this shoulder being formed at an angle of 45 in this instance with the longitudinal axis of the cartridge 13 and die 15.

As a consequence, destructive vibrational movements and forces cause controlled deterioration of the bearing and wear translative element 59, which can be readily replaced in the field by unskilled labor. Previous to this invention, the vibrational movements and forces deteriorated the peripheral edge of the flange of the cartridge 13. The ring clamps are generally manufactured of relatively hard metals such as 4140 steel having an initial Brinell'hardness of about -200. The translative element of the invention may have a Brinell hardness of about 300-500, typical hardnesses for unhardened and flame hardened 0.40 carbon steel. Use of such a translative element prevents deterioration of the edge of the cartridge. The cartridge is preferably of a mild carbon steel (0.20 carbon steel, for example) having a Brinell hardness of about 120. Thus, the translative element is a minimum of substantially 2% times the hardness of the cartridge and may be as high as about 4% times such hardness.

The translative element must not be too thin or its life span will be too short. Also, its thickness must not be too great, or deformations will occur too easily during vibrational movements. A satisfactory range of thicknesses is thought to be from about one-fourth inch (as measured perpendicular to the hypotenuse of the exemplary isosceles right triangle) to about three-fourths inch the actual thickness depending upon the hardnesses of the translative element and the ring clamp.

FIG. 2 is an end view of a preferred embodiment in which translative element 59 has an inner, cylindrical surface 63 that engages a mating cylindrical surface of annular groove 61. One or more apertures 65 having countersunk portions (not shown) are provided for inclusion of recessed countersunk screws (not shown) to attach the translative element 59 to cartridge l3 and prevent rotation therebetween.

The translative element 59 may have a diameter slightly smaller than the diameter of the mating cylindrical surface of groove 61 at the periphery of cartridge 13 for the purpose of achieving an interference fit. Thus, the translative element is in tension effected by being expanded, emplaced'and shrunk onto cartridge 13. As a consequence, friction force alone is often adequate to prevent rotation of the ring. Thus, countersunk apertures 65 and the associated screws are not always necessary.

In employing interference-type assembly, the expanding of translative element 59 is easily accomplished by heating. Accordingly, translative element 59 must be proportioned such that it can be readily heated to a selected temperature and removed before the bulk of the metal in cartridge 13 also reaches that temperature and correspondingly expands. Expressed otherwise, the bulk of the translative element 59 must be so much less than the bulk of the cartridge 13 that the ring can be readily heated, as by a propane torch, and removed before the same temperature is effected in the peripheral members connected with cartridge 13. Moreover, the bearing surface 67 of the translative element should be coextensive with or slightly larger than the mating surface of the clamp 17 to prevent the clamp from bearing directly upon any portion of cartridge 13.

One embodiment that has been found particularly effective is a translative element 59 with an internal cylindrical portion having a diameter of about 24 inches and a length of about 0.375 inch; its outer bearing surface 67 forming an angle of 45 as seen in longitudinal cross section with inner cylindrical surface 63; and its maximum outer diameter being about 24.75 inches.

Ordinarily, translative element 59 is made of 0.40 carbon steel as previously indicated. Other metals or other metals having a hard coated bearing surface can be employed.

While the preferred embodiment employs a unitary translative element of one-piece construction, elements comprised of sectors such as semicircular portions joined and held under clamp 17 may be utilized.

Although the invention has been described with particularity, it should be understood that such description has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may occur without departing from the spirit and the scope of the invention as hereinafter claimed.

lclaim:

1. In a pellet mill having a perforated and rotatable die secured to an outer peripheral edge of a supporting cartridge by a ring clamp, and an interior roller for extruding feed into pellet form through said die, the improvement comprising an annular groove formed in the outer peripheral edge of said cartridge; a removable bearing and wear translative element mating with said groove and held therein by said ring clamp, said element having a hardness to minimize deterioration of the cartridge.

2. The pellet mill improvement defined by claim 1 wherein the hardness of said element is a minimum of substantially 2% times the hardness of the cartridge.

3. The pellet mill improvement defined by claim 2 wherein the thickness of the ring resides in a range from substantially one-fourth to three-fourths inch.

4. The pellet mill of claim 1 wherein said annular groove has a cylindrical outer surface of a first diameter and said wear ring has a cylindrical inner surface of a second diameter normally slightly less than said first diameter and said wear ring is in tension effected by being expanded, emplaced and shrunk onto said outer cylindrical surface.

5. The pellet mill of claim 1 wherein said wear ring is nonrotatably connected with said cartridge.

6. A pellet mill comprising:

a rotatable cartridge having a flange portion;

a cylindrical perforated die carried by the cartridge;

ashaft extendin through the cartridge; v rollers carried y the shaft and engaging the die interior cylindrical surface;

annular groove surfaces formed in the flange portion of the cartridge and in the exterior cylindrical surface of the die;

a removable bearing and wear translative element that mates with the groove in the cartridge flange, said element having a hardness greater than the hardness of the cartridge to minimize deterioration of the cartridge;

a ring clamp having two inwardly protruding shoulders that engage respectively the groove in the die cylindrical surface and the bearing and wear translative element to secure the die to the cartridge.

7. The pellet mill improvement defined by claim 6 wherein the maximum hardness of said element is a minimum of substantially 2% times the hardness of said clamp.

8. The pellet mill improvement defined by claim 7 wherein the thickness of the ring resides in a range from substantially one-eighth to one-half inch.

9. The pellet mill of claim 6 wherein said annular groove has a cylindrical outer surface of a first diameter and said wear ring has a cylindrical inner surface of a second diameter normally slightly less than said first diameter and said wear ring is in tension effected by being expanded, emplaeed and shrunk onto said outer cylindrical surface.

10. The pellet mill of claim 6 wherein said wear ring is nonrotatably connected with said cartridge. 

1. In a pellet mill having a perforated and rotatable die secured to an outer peripheral edge of a supporting cartridge by a ring clamp, and an inteRior roller for extruding feed into pellet form through said die, the improvement comprising an annular groove formed in the outer peripheral edge of said cartridge; a removable bearing and wear translative element mating with said groove and held therein by said ring clamp, said element having a hardness to minimize deterioration of the cartridge.
 2. The pellet mill improvement defined by claim 1 wherein the hardness of said element is a minimum of substantially 2 1/2 times the hardness of the cartridge.
 3. The pellet mill improvement defined by claim 2 wherein the thickness of the ring resides in a range from substantially one-fourth to three-fourths inch.
 4. The pellet mill of claim 1 wherein said annular groove has a cylindrical outer surface of a first diameter and said wear ring has a cylindrical inner surface of a second diameter normally slightly less than said first diameter and said wear ring is in tension effected by being expanded, emplaced and shrunk onto said outer cylindrical surface.
 5. The pellet mill of claim 1 wherein said wear ring is nonrotatably connected with said cartridge.
 6. A pellet mill comprising: a rotatable cartridge having a flange portion; a cylindrical perforated die carried by the cartridge; a shaft extending through the cartridge; rollers carried by the shaft and engaging the die interior cylindrical surface; annular groove surfaces formed in the flange portion of the cartridge and in the exterior cylindrical surface of the die; a removable bearing and wear translative element that mates with the groove in the cartridge flange, said element having a hardness greater than the hardness of the cartridge to minimize deterioration of the cartridge; a ring clamp having two inwardly protruding shoulders that engage respectively the groove in the die cylindrical surface and the bearing and wear translative element to secure the die to the cartridge.
 7. The pellet mill improvement defined by claim 6 wherein the maximum hardness of said element is a minimum of substantially 2 1/2 times the hardness of said clamp.
 8. The pellet mill improvement defined by claim 7 wherein the thickness of the ring resides in a range from substantially one-eighth to one-half inch.
 9. The pellet mill of claim 6 wherein said annular groove has a cylindrical outer surface of a first diameter and said wear ring has a cylindrical inner surface of a second diameter normally slightly less than said first diameter and said wear ring is in tension effected by being expanded, emplaced and shrunk onto said outer cylindrical surface.
 10. The pellet mill of claim 6 wherein said wear ring is nonrotatably connected with said cartridge. 